With the recent trend toward large-sized and large-capacity application apparatuses, a power semiconductor device having a high breakdown voltage, a high current capacity, and high-speed switching characteristics has become necessary.
Accordingly, many researches and developments are being conducted on MOSFETs (metal oxide semiconductor field effect transistors) using silicon carbide (SiC), instead of conventional MOSFETs using silicon. Particularly, there is a lot of development of vertical trench MOSFETs.
In the case of a vertical trench MOSFET, a breakdown occurs which can damage an oxide film due to an electric field concentration effect by which an electric field is concentrated at the bottom of a gate. This causes a premature breakdown which exhibits a breakdown voltage much lower than a breakdown voltage caused by the intrinsic threshold voltage of a raw material of the MOSFET.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept and therefore it may contain information that does not form the prior art.